What Is the Prevalence of Tinnitus Worldwide?--Part 1

What Is the Prevalence of Tinnitus Worldwide?--Part 1

What is the prevalence of tinnitus worldwide? As audiologists, the answer to this question may be something that we are interested in knowing. Unfortunately, a recent systematic review, conducted by McCormack et al (2016), suggests that it may not be an easy question to answer.

These authors, who used the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines (Moher et al. and the PRISMA Group, 2009), searched for research studies in five electronic databases to answer this question, as well as determine the prevalence of “bothersome” tinnitus worldwide. They also sought to explore reasons for differences in prevalence across studies. The authors limited their search to studies that met the following criteria:

Conducted between the dates of January 1, 1980, and July 1, 2015 (when their search was conducted)

Had subjects 18 years of age or older

Were not limited to a restricted set of the population (e.g., those with certain types of exposures)

Was not a case-control study

Based on their extensive review of 39 studies (reported in 40 articles) determined to meet the aforementioned criteria, the authors found wide prevalence ranges for both tinnitus, in general, and “bothersome” tinnitus, specifically.

“Overall tinnitus prevalence figures for each study ranged from 5.1% (Quaranta, Assennato, and Sallustio, 1996) to 42.7% (Gibrin, Melo, and Marchiori, 2013). Tinnitus severity was assessed in 16 studies. The prevalence of bothersome tinnitus ranged from 3.0% (Michikawa, Nishiwaki, Kikuchi, Saito, Mizurati, Okamato, and Takebayashi, 2010) to 30.9% (Kim, Lee, An, Sim, Park, Kim, Lee, Hong, and Choi, 2015). Even comparing those studies that used the most common type of tinnitus question (‘tinnitus lasting for more than five minutes at a time’), the prevalence figures reported for current tinnitus vary widely from 11.9% (Fuiji,Nagata, Nakamura, Kawachi, Takatsuka, Oba, and Shimizu,2011) to 30.3% (Sindhusake, Mitchell, Newall, Golding, Rochtchina, and Rubin, 2003).”

The authors also noted differences in prevalence based on both age and sex. In general, prevalence increased with age up to about age 70 years and was greater in males versus females. The findings regarding bothersome tinnitus, however, were mixed regarding sex.

McCormack and colleagues (2016) note several problems with determining the prevalence numbers worldwide. The problems include: (1) lack of a universal definition for both tinnitus and bothersome tinnitus and distinguishing between the two; (2) differences between studies in terms of how age groups were reported; (3) geographic bias; and (4) moderate to high reporting bias in the majority of the studies. Unfortunately, the prevalence of tinnitus remains unclear. To address this, the authors call for standardization in future research when it comes to (1) tinnitus definitions and how it is assessed, and (2) reporting formats.